1. Field of the Invention
The invention relates to a method of manufacturing a coated material comprising solid fragments coated with a binder, the method comprising a stage of drying of the solid fragments followed by a stage of coating of the entirety of the solid fragments with binder, in particular with hot binder.
“Solid fragments” is taken to mean all solid fragments usable for forming coated materials in particular for road building, comprising in particular natural mineral granular materials and aggregates of coated materials resulting from the recycling of materials recovered from the repairing of roads.
“Binder” is taken to mean any hydrocarbon binder of fossil or vegetable origin which is usable for the formation of coated materials, in particular pure bitumen or bitumen with fluxing agents and/or liquefying agents added and/or bitumen modified by the addition of polymers, this binder being possibly presented in the form of an emulsion or foam.
2. Description of the Related Art
In the conventional method for hot coating, the drying stage is carried out so as to eliminate substantially entirely the humidity in the granular materials, which requires a considerable expense of energy clue to the large quantity of water initially contained in the granular materials. Moreover, the drying and increase in temperature bring about the release of vapours containing steam charged with dusts. Taking into account their large quantity, these vapours are difficult to process and the application of the method therefore leads to substantial pollution of the environment.
To solve this problem, EP 1 469 038 proposes to apply the drying stage to a first part of the granular materials, substantially devoid of fines, then to coat this first part with hot bitumen, and then to add to the mix thus obtained a second part of the granular materials comprising sands and fines.
This method requires two fractions of granular materials to be available, one devoid of fines and the other containing fines, which may lead to problems. Moreover, this method cannot be put into practice efficiently in certain existing coating installations, and may therefore necessitate costly adaptation thereof.